The present invention relates to a deep boring mill with a synchroneously operable headstock, particularly to a horizontal boring mill for drilling holes of substantial depth. Such mills have a machine bed for supporting the respective headstock and the tailstock, whereby the headstock is movable by respective drive means. Further, such machines are equipped with a cooling medium supply device operatively arranged intermediate the head- and tailstock. Normally, the cooling medium supply device performs a clamping movement or participates in such movement. In deep boring mills of this type the boring tool is pulled into the cooling medium supply device for removing the work piece from the mill. This removal is accomplished by moving or displacing the headstock and thus the tool carrying boring tube along the machine bed. Thereafter, the cooling medium supply device which clamps the work piece, is displaced in the release direction. As a result, however, the boring tool again protrudes from the cooling medium supply device so that it is possible that the work piece as well as the tool may be damaged when the work piece is being removed. In order to avoid such damage it is necessary in the prior art to further displace the headstock in order to again pull the tool into the cooling medium supply device. This type of machine operation is time consuming and hence troublesome.
If a work piece is to be clamped in such a boring mill, the operational procedure becomes even more complicated. After the work piece has been placed into the boring mill, the tool must be moved out of the cooling medium supply device to such an extent that the tool does not yet contact the work piece. Thereafter, the cooling medium supply device may be displaced in the clamping direction to the same extent. Even work pieces of the same length may take up different axial positions upon insertion into the mill. Therefore, it is possible that it becomes necessary to repeat the just described movement sequence several times until the cooling medium supply device has displaced the work piece to such an extent that it contacts the tailstock, whereupon it may be clamped with the next displacement movement of the cooling medium supply device.
The operation of the above described machines could be simplified and thereby the operational time per work piece reduced if the so-called plunging space available for the boring tool in the cooling medium supply device would be sufficiently deep in order to permit all movements that are required to be performed by the cooling medium supply device without moving the boring tool for this purpose. Such a solution is basically possible, however, it requires a cooling medium supply device of substantial or very large size which in turn calls for a correspondingly longer machine bed.